Experimental work has been carried out with a hydraulic flow test rig in which flows of water up to 65 kgs-l can be measured with a weigh-tank and its diverter valve to an accurary of ± 0.2%. The nature of the experimental work has been to investigate the system pressure losses due to the components in line (i) For interference free flow; (ii) For interactions. The components used are 90 degree circular bends and orifice plates. Bends of radius ratios from R/D - 1.49 to 4.89 and nominally standard single-hole and multi-hole orifice plates of area ratios from m – 0.170 to 0.508 have been tested. To investigate the interaction effects arising from an orifice plate in proximity to bends, various bend-orifice plate (in a few instances orifice plate-bend) combinations have been arranged. The bore diameter of duct (or pipe) and bend is approximately D – 145.05 mm and tests have been performed for Reynolds numbers ranging from Re(D) – 0.7 x 105 to 6 x 10(5). In those instances in which results from the experimental work can be compared directly with published results, agreement is good. However, many of the experimental results, particularly the measurements of interactions between bends and orifice plates, are new.

8 pp. / az1329: Measuring Water Flow in Surface Irrigation Ditches and Gated Pipe Martin, E.C. 2000. Determining the Amount of Water Applied to a Field. Cooperative Extension Pub. No. AZ1157, Arizona Water Series No. 29. University of Arizona, Tucson, AZ. Martin, E.C. 1999. Measuring Water Flow and Rate on the Farm. Cooperative Extension Pub. No. AZ1130, Arizona Water Series No. 24. University of Arizona, Tucson, AZ. / Measuring water is a critical part of any irrigation management system. This informational bulletin gives some simplistic methods of measuring flow rate in an open ditch and in gated pipe. Using the float method, dye tracers and velocity head meters, growers can get a quick estimate of the flow in their farm ditch. From this, an estimate of water applied or a set time can be determined. The bulletin also explains how a propeller meter works for gated pipe. Gated pipe is widely used through the state and in the West.

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An ever-expanding global industry focuses attention on energy supply and use. Cost-effective electrical energy production and reduced consumption pave the way for this expansion. Eskom’s demand-side management (DSM) initiative provides the opportunity for reduced electricity consumption with cost-effective implementation for their respective clients. South African gold mines have to extend their operations to up to 4000 m below the surface to maintain profitable operations. Deep-level mining therefore requires large and energy-intensive cooling installations to provide safe working conditions. These installations generally consist of industrial chillers, cooling towers, bulk air coolers and water transport systems. All of these components operate in unison to provide chilled service water and cooled ventilation air underground. In this study the improved energy efficiency and control of a South African gold mine’s cooling plant is investigated. The plant is separated into a primary and secondary cooling load, resulting in a cascading cooling system. Necessary research was conducted to determine the optimal solution to improve the plant’s performance and electrical energy usage. Variable speed drives (VSD) were installed on the chiller evaporator and condenser water pumps to provide variable flow control of the water through the chillers, resulting in reduced motor electricity usage. Potential electricity savings were simulated. Proposed savings were estimated at 600 kW (13.6%) daily, with an expected saving of R 2 275 000 yearly, resulting in a payback period of less than 9 months. Results indicated are based on total savings, as VSD savings and control savings were combined. The VSDs that were installed, were controlled according to an optimum simulation model’s philosophy. A real-time energy management program was used to control the VSDs and monitor the respective systems. The program’s remote capabilities allow for off-site monitoring and control adjustments. A control strategy, which was implemented using the management program, is discussed. Energy efficiency was achieved through the respective installations and control improvements. The results were analysed over an assessment period of three months to determine the viability of the intervention. A newly installed Bulk Air Cooler (BAC) added to the service delivery of the cooling plant post installation of the VSDs. Focusing on service delivery to underground showed a savings of 1.7 MW (33.6%) daily and a payback period of 3.6 months (0.3 years). The overall implementation showed an average energy saving of 2.3 MW (47.1%) daily, with the result that a daily saving of R 23 988.20 was experienced, reducing the payback period to 2.3 months (0.2 years). Through the installation of energy-efficiency technology and a suitable control philosophy, a cost-effective, energy-efficiency improvement was created on the case-study cooling plant. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

An ever-expanding global industry focuses attention on energy supply and use. Cost-effective electrical energy production and reduced consumption pave the way for this expansion. Eskom’s demand-side management (DSM) initiative provides the opportunity for reduced electricity consumption with cost-effective implementation for their respective clients. South African gold mines have to extend their operations to up to 4000 m below the surface to maintain profitable operations. Deep-level mining therefore requires large and energy-intensive cooling installations to provide safe working conditions. These installations generally consist of industrial chillers, cooling towers, bulk air coolers and water transport systems. All of these components operate in unison to provide chilled service water and cooled ventilation air underground. In this study the improved energy efficiency and control of a South African gold mine’s cooling plant is investigated. The plant is separated into a primary and secondary cooling load, resulting in a cascading cooling system. Necessary research was conducted to determine the optimal solution to improve the plant’s performance and electrical energy usage. Variable speed drives (VSD) were installed on the chiller evaporator and condenser water pumps to provide variable flow control of the water through the chillers, resulting in reduced motor electricity usage. Potential electricity savings were simulated. Proposed savings were estimated at 600 kW (13.6%) daily, with an expected saving of R 2 275 000 yearly, resulting in a payback period of less than 9 months. Results indicated are based on total savings, as VSD savings and control savings were combined. The VSDs that were installed, were controlled according to an optimum simulation model’s philosophy. A real-time energy management program was used to control the VSDs and monitor the respective systems. The program’s remote capabilities allow for off-site monitoring and control adjustments. A control strategy, which was implemented using the management program, is discussed. Energy efficiency was achieved through the respective installations and control improvements. The results were analysed over an assessment period of three months to determine the viability of the intervention. A newly installed Bulk Air Cooler (BAC) added to the service delivery of the cooling plant post installation of the VSDs. Focusing on service delivery to underground showed a savings of 1.7 MW (33.6%) daily and a payback period of 3.6 months (0.3 years). The overall implementation showed an average energy saving of 2.3 MW (47.1%) daily, with the result that a daily saving of R 23 988.20 was experienced, reducing the payback period to 2.3 months (0.2 years). Through the installation of energy-efficiency technology and a suitable control philosophy, a cost-effective, energy-efficiency improvement was created on the case-study cooling plant. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

Apresenta-se um modelo matemático que avalia numericamente a estabilidade do estado estacionário para escoamentos água-ar em sistemas pipeline-riser de geometria variável. Uma análise a partir da teoria de estabilidade linear é aplicada a um modelo matemático adequado ao escoamento água-ar no sistema pipeline-riser. O modelo considera equações de continuidade para a fase líquida e para a fase gasosa, admite-se escoamento unidimensional e em condição isotérmica. O líquido é considerado incompressível enquanto que a fase gasosa é considerada um gás ideal. Admite-se uma equação de momento simplificada para mistura onde despreza-se a inércia (NPW - Modelo No Pressure Wave) e o padrão de escoamento local é definido com base nas condições do escoamento e na inclinação local. Assim, a intermitência severa é controlada principalmente pela gravidade no riser e pela compressibilidade do gás no pipeline. Tanto a correlação de fluxo de deriva quanto o cálculo da queda de pressão por atrito, adotados como lei de fechamento do modelo, são determinados em função do padrão de escoamento. Injeção de gás e válvula de choke são consideradas, respectivamente, na base e no topo do riser. O modelo é aplicado à sistemas pipeline-riser com escoamento água-ar citados na literatura. Os resultados da análise de estabilidade linear numérica são comparados aos resultados experimentais e numéricos apresentando uma excelente concordância. / A mathematical model that numerically evaluates the stability of the stationary state for hilly terrain air-water flows systems is presented. Numerical linear stability analysis is performed to a suitable mathematical model for the two-phase flows in a pipeline-riser system. The mathematical model considers the continuity equations for the liquid and gas phases, one-dimensional flow and isothermal conditions. The liquid is assumed incompressible while the gas phase is considered as an ideal gas. A simplified momentum equation for the mixture, neglecting inertia (NPW - No pressure wave model) is considered and the local flow pattern is defined based on the flow conditions and the local inclination. In this way, severe slugging is controlled mainly by gravity in the riser and compressibility in the pipeline. The void fraction and friction pressure drop, utilized as closure laws, are determined based on the local flow pattern. Gas injection at the bottom of the riser and a choke valve at the top are considered. The model is applied to air-water pipeline-riser systems reported in the literature. Numerical linear stability analysis results are compared with experimental and numerical results reported in the literature with excellent agreement.

Les aquifères karstiques sont caractérisés par un écoulement rapide dans les conduits karstiques et un écoulement lent dans la roche encaissante (matrice). En raison de cet écoulement rapide, ces aquifères sont fortement vulnérables à la pollution. L'objectif principal de cette thèse est d’évaluer l'importance des échanges d'eau à l'interface entre les conduits et la matrice et par conséquent l’impact de ces échanges sur le transport de soluté dans le système karstique. Pour investiguer l’apport de l'équation de Brinkman à l’évaluation des écoulements d'eau, un modèle dont la géométrie du conduit est décrite par la fonction sinus a été établi. Deux scénarii sont appliqués. Le scénario A emploie la loi de Darcy dans le conduit et la matrice. Le scénario B emploie l'équation de Brinkman et la loi de Darcy dans le conduit et la matrice, respectivement. Le terme supplémentaire de l’équation de Brinkman décrivant les forces de cisaillement joue un rôle prédominant sur l'échange d’eau entre le conduit et la matrice lorsque les conduits sont sinueux. Le modèle hydrodynamique - transport a été appliqué au système karstique du Val d’Orléans. La calibration a démontré que le meilleur diamètre moyen du conduit est de 5 m, la perméabilité dans la roche encaissante est de 5,7×10-10 m2 et celle du conduit de 1,65×10-5 m2 à 5,5×10-5 m2. Les prédictions du modèle hydrodynamique - transport ont été comparées aux crues de la Loire observées dans les années 1992 et 1993 durant lesquelles les concentrations en chlorure (traceur naturel conservatif) ont été dosées dans la Loire et à la source du Bouillon. Avec un coefficient d’emmagasinement dans la matrice de 0,9 m-1, la distance pénétrée par l'eau de la crue dans la matrice est d'environ 530 m en deux mois pour une crue de 2 m (exemple de 1993). / The karst aquifers are characterized by a fast flow in the karstic conduits and a slow flow in the matrix. Because of this fast flow, these aquifers are strongly vulnerable to pollution. The main aim of this thesis is to evaluate the importance of water exchanges at the interface between the conduits and the matrix and by consequence the impact of these exchanges on the solute transport in the karst system. To investigate the contribution of the Brinkman equation to the evaluation of the water flows, a model whose geometry of the conduit is described by the sine function was established. Two scenarii are applied. Scenario A employs Darcy’s law in the conduit and the matrix. The scenario B employs the Brinkman equation and Darcy’s law in the conduit and the matrix, respectively. The additional term of the Brinkman equation describing the shear stress plays a predominant role on the water exchange between the conduit and the matrix when the conduits are sinuous. The hydrodynamic - transport model was applied to the karst system of the Val d’Orléans. The calibration showed that the best average diameter of the conduit is of 5 m, the permeability in the hosted rock is of 5.7×10-10 m2 and that of the conduit of 1.65×10-5 m2 to 5.5×10-5 m2. The results of the hydrodynamic - transport model were compared to floods of the Loire observed in the years 1992 and 1993 during which the chloride concentrations (tracer conservative naturalness) were proportioned in the Loire and Bouillon Spring. With a storage coefficient in the matrix 0.9 m-1, the distance penetrated by the water in the matrix is approximately 530 m in two months for a rising of 2 meters (example of 1993).

Seagrass communities are composed of numerous organisms that depend on water-column nutrients for metabolic processes. The rate at which these organisms remove a nutrient from the water column can be controlled by physical factors such as hydrodynamic regime or by biological factors such as speed of enzyme reactions. The impact of hydrodynamic regime on rates of nutrient uptake for seagrass (Thalassia testudinum) communities and for organisms that comprise the community (seagrass, epiphytes, phytoplankton, and microphytobenthos) was quantified in a series of field flume experiments employing the use of 15N-labeled ammonium and nitrate. Rates of ammonium uptake for the entire community and for seagrass leaves and epiphytes were significantly dependent on bulk velocity, bottom shear stress, and the rate of turbulent energy dissipation. Relationships between uptake rates and these parameters were consistent with mass-transfer theory and suggest that the effect of water flow on ammonium uptake is the same for the benthos as a whole and for the organisms that form the canopy. In addition, epiphytes on the surface of T. testudinum leaves were shown to depress leaf uptake by an amount proportional to the area of the leaf covered by epiphytes. Water flow influenced rates of nitrate uptake for the community and the epiphytes; however, uptake rates were depressed relative to those for ammonium suggesting that uptake of nitrate was also affected by biological factors such as enzyme activity. Epiphytes reduced uptake of nitrate by the leaves; however, the amount of reduction was not proportional to the extent of epiphyte cover, which provided further evidence that nitrate uptake by T. testudinum leaves was biologically limited. As an additional component of the research, hydrodynamic regime of a mixed seagrass and coral community in Florida Bay was characterized using an acoustic Doppler velocimeter. Hydrodynamic parameters estimated from velocity data were used in mass-transfer equations to predict nutrient uptake by the benthos over a range of water velocity. Measured rates of uptake from field flume experiments conducted in the same community confirmed that hydrodynamic data could be used to accurately predict nutrient transport to the benthos under natural flow conditions.

<p>The carbon metabolism in costal sediments is of major importance for the global carbon cycle. Costal sediments are also subjected to physical forcing generating water fluxes above and through the sediments, but how the physical affect the carbon metabolism is currently poorly known. In this study, the effect of advective pore water flow on degradation of organic matter in permeable sandy sediment was investigated in a laboratory study during wintertime. Sediments were collected from both brackish water (Askö) and from a fresh water stream (Getå Stream). In two chamber experiments, with and without advective pore water flow, the degradation of organic matter was measured through carbon dioxide analysis from water and headspace. In Askö sediments mineralization rates ranged from 3.019 - 5.115 mmol C m-2 d-1 and 3.139 mmol C m-2 d-1 with and without advective pore water flow, respectively. Those results correspond with results from earlier studies of carbon mineralization rates in sediment in the North Sea and the Baltic Sea. There were no significant differences between the two groups in the Askö sediment. In Getå Stream sediments mineralization rates ranged between 4.059 mmol C m-2 d-1 and 6.806 mmol C m-2 d-1 with and without advective flow, respectively. The mineralization rates for Getå Stream correspond with earlier studies of carbon mineralization rates in a stream in New Hampshire.</p>

Shallow water flow and lost circulation are frequently encountered problems during drilling top holes of oil, gas or geothermal wells. Plenty of methods have been applied to overcome these problems. Placement of silicate based gel systems is one of the oldest methods to seal such undesired zones. For this study, sodium-silicate based gel system is investigated experimentally. This gel system is deliberately delayed multi-component system mixed as a uniform liquid at the surface but desired to form strong gel where it is placed in the well. The experimentally analyzed system is composed of distilled water, sodium-silicate solution, polymer solution, lost circulation materials, weighting agent and organic initiator. In this study, effect of these components on gel time, gel quality and gel strength at room temperature is investigated as a function of their concentration. To be able to compare gelation time of different compositions, gel time tests were performed by following the developed method in this study. Observation codes were defined to be able to compare the gel qualities of different compositions. For gel time and quality tests, sodium-silicate concentrations from 3.5% to 15% were studied and the concentrations between 7.5% and 10% were found as optimum. Gel time is getting higher as silicate-initiator ratio (SIR) increases for these optimum concentrations. It was also determined that, addition of polymers reduces the gel time and increases the elasticity of the resulting gels. Long term gelation process was investigated by monitoring turbidity (NTU) of the mixtures and plotting NTU versus time curves. Viscosity development curves obtained from rotational viscometer at various constant shear rates indicated reduced gelation times with increasing shear rate. Furthermore, by using modified High-Pressure, High-Temperature filter press cell, it was determined that, addition of lost circulation materials increases the extrusion pressure.